const ref rvalues

[Denis Koroskin]

On Mon, 14 Dec 2009 21:06:20 +0300, dsimcha <dsimcha at yahoo.com> wrote:

> I mentioned this deep in another thread, but I think it deserves its own
> thread.  Can we get something like:
>
> void doStuff(T)(const ref T val) {
>     // do stuff.
> }
>
> T getVal() {
>     return someValue;
> }
>
> void main() {
>     doStuff(getVal());  // Doesn't currently work.
> }
>
> For non-const ref parameters, it's understandable that passing rvalues in
> doesn't work because this is likely a bug that the compiler should catch.
> However, for const ref parameters, can't the compiler just implicitly  
> put the
> value on the caller's stack frame and convert it to an lvalue rather than
> forcing the programmer to write the boilerplate to do this manually?   
> This
> would result in:
>
> doStuff(getVal()); -->
>
> auto __temp = getVal();
> doStuff(__temp);

I agree it hurts a lot. I faced the same problem implementing RefCounted:  
you can't return RefCounted object from one function and pass it by  
reference to another one. Passing it by value is not a good option.